12" Triangular Scale Ruler Engineer 1:10, 1:20, 1:30, 1:40, 1:50, 1:60 Etched grooves, NOT just printed Essential tool for engineers. Compare to Staedtler and Helix - these are higher quality with inked grooves.. NOT just printed on. 12 Inches Triangular divided 10, 20, 30, 40, 50 and 60 parts to the inch. Inked Grooves High Quality. Hi Quality Plastic Core Made in Germany